# Do clear properties take up space in the DB.

Gevan Dutton (shanos@es.co.nz)
Sun, 22 Dec 1996 14:38:33 PST

- Messages sorted by:[ date ][ thread ][ subject ][ author ]

    On Sun, 22 Dec 1996, Francis Litterio wrote:

    > I'm considering adding a new property to #1 which will be clear on
    > nearly every object in the DB except a very few.  Will doing so bloat my
    > DB (in memory and on disk) by much?  I guess I'm wondering whether
    > having a property on every object that is clear 99.99% of the time will
    > take up much space (compared to not having that property at all).

    Standard disclaimers apply:

    Well, AFAIK, it'll add ~16[1] bytes (memory) to the size of every
    descendant of #1, even if that property is clear on those objects.  This
    is the cost of creating a struct Pval for that property on the
    descendants, which stores value, ownership and permission info for the
    property on each object.  If the property is clear on an object, then a
    special (type) value is stored in the value part.

    I'm not so sure about space used on disk.  I'd guess that information is
    stored for clear properties there, too, but the space required isn't so
    clear because it's text. ;)

    [1] 14 is probably about the minimum you can expect, it's increased to 16
    to keep things aligned nicely on the machine I'm running on.